1. Technical Field
The present invention relates to a multimeter in which a plurality of selection terminal holes for inserting a connector of a test probe thereinto is selectively opened in accordance with a rotation of a rotary switch for selecting a measurement function.
2. Background of the Invention
A multimeter (called a tester) which is a measurement unit with a plurality of measurement functions for measuring a voltage, a current, a resistance, and the like is used in various measurement sites. The multimeter includes a common terminal hole into which a black test probe is inserted and a plurality of selection terminal holes into which a connector of a red test probe is inserted. Then, a measurer selects a desired measurement function by rotating a rotary switch and performs a measurement by inserting the red test probe into the selection terminal hole corresponding to the selected measurement function and inserting the black test probe into the common terminal hole.
In a case where the measurer uses the multimeter by inserting the test probe into the erroneous selection terminal hole, a circuit or a fuse inside the multimeter may be damaged. For example, a maximum current that may flow to the current measurement selection terminal hole is defined. Accordingly, when the current measurement selection terminal hole is used by mistake for the other measurement function, there is a case in which the fuse may be damaged due to the excessive current flowing thereto. For this reason, for example, as disclosed in Japanese Patent No. 3522030, there is known a multimeter with an erroneous insertion preventing mechanism in which a shutter plate is moved by a rotation of a rotary switch so as to open a selection terminal hole corresponding to a measurement function.